package server;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.*;

/**
 * Minicat的主类
 */
public class Bootstrap {

    /**
     * 定义socket监听的端口号
     */
    private int port = 8080;

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }


    /**
     * Minicat启动需要初始化展开的一些操作
     */
    public void start() throws Exception {

        // 加载解析相关的配置，web.xml
        loadServlet();

        loadServerXml();

        // 定义一个线程池
        int corePoolSize = 10;
        int maximumPoolSize = 50;
        long keepAliveTime = 100L;
        TimeUnit unit = TimeUnit.SECONDS;
        BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>(50);
        ThreadFactory threadFactory = Executors.defaultThreadFactory();
        RejectedExecutionHandler handler = new ThreadPoolExecutor.AbortPolicy();


        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                corePoolSize,
                maximumPoolSize,
                keepAliveTime,
                unit,
                workQueue,
                threadFactory,
                handler
        );

        /*
            完成Minicat 1.0版本
            需求：浏览器请求http://localhost:8080,返回一个固定的字符串到页面"Hello Minicat!"
         */
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("=====>>>Minicat start on port：" + port);

        /*while(true) {
            Socket socket = serverSocket.accept();
            // 有了socket，接收到请求，获取输出流
            OutputStream outputStream = socket.getOutputStream();
            String data = "Hello Minicat!";
            String responseText = HttpProtocolUtil.getHttpHeader200(data.getBytes().length) + data;
            outputStream.write(responseText.getBytes());
            socket.close();
        }*/


        /**
         * 完成Minicat 2.0版本
         * 需求：封装Request和Response对象，返回html静态资源文件
         */
        /*while(true) {
            Socket socket = serverSocket.accept();
            InputStream inputStream = socket.getInputStream();

            // 封装Request对象和Response对象
            Request request = new Request(inputStream);
            Response response = new Response(socket.getOutputStream());

            response.outputHtml(request.getUrl());
            socket.close();

        }*/


        /**
         * 完成Minicat 3.0版本
         * 需求：可以请求动态资源（Servlet）
         */
        /*while(true) {
            Socket socket = serverSocket.accept();
            InputStream inputStream = socket.getInputStream();

            // 封装Request对象和Response对象
            Request request = new Request(inputStream);
            Response response = new Response(socket.getOutputStream());

            // 静态资源处理
            if(servletMap.get(request.getUrl()) == null) {
                response.outputHtml(request.getUrl());
            }else{
                // 动态资源servlet请求
                HttpServlet httpServlet = servletMap.get(request.getUrl());
                httpServlet.service(request,response);
            }

            socket.close();

        }
*/

        /*
            多线程改造（不使用线程池）
         */
        /*while(true) {
            Socket socket = serverSocket.accept();
            RequestProcessor requestProcessor = new RequestProcessor(socket,servletMap);
            requestProcessor.start();
        }*/


        System.out.println("=========>>>>>>使用线程池进行多线程改造");
        /*
            多线程改造（使用线程池）
         */
        while (true) {
            Socket socket = serverSocket.accept();
            RequestProcessor requestProcessor = new RequestProcessor(socket, servletMap);
            //requestProcessor.start();
            threadPoolExecutor.execute(requestProcessor);
        }


    }


    private Map<String, HttpServlet> servletMap = new HashMap<String, HttpServlet>();

    private static String appBase = "D:\\MyProject\\Minicat\\webapps";

    /**
     * 加载解析web.xml，初始化Servlet
     */
    private void loadServlet() {
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream("web.xml");
        SAXReader saxReader = new SAXReader();

        try {
            Document document = saxReader.read(resourceAsStream);
            Element rootElement = document.getRootElement();
            WebClassLoader webClassLoader = new WebClassLoader();
            List<Element> selectNodes = rootElement.selectNodes("//servlet");
            for (int i = 0; i < selectNodes.size(); i++) {
                Element element = selectNodes.get(i);
                // <servlet-name>lagou</servlet-name>
                Element servletnameElement = (Element) element.selectSingleNode("servlet-name");
                String servletName = servletnameElement.getStringValue();
                // <servlet-class>server.LagouServlet</servlet-class>
                Element servletclassElement = (Element) element.selectSingleNode("servlet-class");
                String servletClass = servletclassElement.getStringValue();
                // 根据servlet-name的值找到url-pattern
                Element servletMapping = (Element) rootElement.selectSingleNode("/web-app/servlet-mapping[servlet-name='" + servletName + "']");
                // /lagou
                String urlPattern = servletMapping.selectSingleNode("url-pattern").getStringValue();
                servletMap.put(urlPattern, (HttpServlet) Class.forName(servletClass).newInstance());
            }
            File file = new File(appBase);
            File[] files = file.listFiles();

            for (File f : files) {
                webClassLoader.findClass("server.HttpServlet", f.getPath());
                webClassLoader.findClass("server.Servlet", f.getPath());
            }
        } catch (DocumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

    }


    /**
     * 加载server.xml文件
     */
    public void loadServerXml() throws DocumentException {
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream("server.xml");
        SAXReader saxReader = new SAXReader();
        Document document = saxReader.read(resourceAsStream);
        Element rootElement = document.getRootElement();
        Element engineElement = (Element) rootElement.selectSingleNode("//Engine");
        //<Engine name="localhost" appBase="D:\MyProject\Minicat\webapps"></Engine>
        String appBase = engineElement.attributeValue("appBase");

        File file = new File(appBase);
        File[] files = file.listFiles();

        for (File f : files) {
            String path = f.getPath();
            String webXmlPath = path + File.separatorChar + "web.xml";
            System.out.println("web.xml path： " + webXmlPath);
            loadWebXml(webXmlPath, appBase, path);
        }
    }

    /**
     * 加载web.xml
     *
     * @param webXmlPath    webxml文件路径
     * @param appBase       应用文件存放根目录
     * @param classBasepath D:\MyProject\Minicat\webapps\demo1
     * @throws FileNotFoundException
     * @throws DocumentException
     */
    public void loadWebXml(String webXmlPath, String appBase, String classBasepath) {
        try {
            FileInputStream fileInputStream = new FileInputStream(webXmlPath);
            SAXReader saxReader = new SAXReader();
            Document document = saxReader.read(fileInputStream);
            Element rootElement = document.getRootElement();

            Element servletElement = (Element) rootElement.selectSingleNode("//servlet");
            Element servletNameElement = (Element) servletElement.selectSingleNode("servlet-name");
            Element servletClassElement = (Element) servletElement.selectSingleNode("servlet-class");

            String servletName = servletNameElement.getStringValue();
            String servletClass = servletClassElement.getStringValue();
            //从根节点过滤符合条件的Element
            Element servletMappingElement = (Element) rootElement.selectSingleNode("/web-app/servlet-mapping[servlet-name='" + servletName + "']");
            //加载类
            WebClassLoader webClassLoader = new WebClassLoader();
            Class<?> aClass = webClassLoader.findClass(servletClass, classBasepath);
            System.out.println("classBasepath: " + classBasepath);
            String urlPattern = servletMappingElement.selectSingleNode("url-pattern").getStringValue();

            String substring = classBasepath.substring(classBasepath.lastIndexOf('\\') + 1);
            String requestUrl = "/" + substring + urlPattern;
            System.out.println("requestUrl:" + requestUrl);
            //实例化servlet
            servletMap.put(requestUrl, (HttpServlet) aClass.newInstance());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * Minicat 的程序启动入口
     *
     * @param args
     */
    public static void main(String[] args) {
        Bootstrap bootstrap = new Bootstrap();
        try {
            //bootstrap.loadServerXml();
            // 启动Minicat
            bootstrap.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
